The other angle is that this is a privacy measure. Sometimes Google Assistant devices like the Google Home get triggered by words that sounds like “OK Google” or “Hey Google”, thus recording people talking when it was unwanted. The fact that Google’s storing of audio is somewhat a grey area, it might help people lessen the accidental recording of private conversations.
That said, if you’re that worried about a device in your home freely recording you, you probably won’t own a physical voice assistant or use one on your device.
Google confirmed to The Verge that the feature is to “roll out gradually” to Google Assistant devices.